1. Field of the invention
The present invention relates to a laminated capacitor and, more particularly, to an arrangement of a laminated capacitor of a feed-through type.
2. Description of the Prior Art
Conventionally, many types of feed-through capacitors are proposed for eliminating or reducing unwanted high frequency noise signals. Such feed-through capacitors are so designed that they can be easily mounted on a chassis without any difficulty, but they are not suitable for being mounted on a circuit board.
To facilitate the mounting of a capacitor on a circuit board, a chip shaped feed-through type laminated capacitor 1, such as shown in FIG. 1, has been proposed. According to the laminated capacitor 1 shown in FIG. 1, first type dielectric sheets 2 and second type dielectric sheets 3 are laminated alternately, and another dieletric sheet 11 is further laminated. Then, external electrodes 4, 5 and 6 are provided so as to enable the mounting of the capacitor on a circuit board. FIG. 2 shows a manner in which dielectric sheets 2 and 3 are arranged. Dielectric sheet 2 has a rectangular configuration defined by four sides 7a, 7b, 7c and 7d and is provided with a stripe shaped electrode 8 extending between sides 7a and 7b for receiving or producing signals. Similarly, dielectric sheet 3 has a rectangular configuration defined by four sides 9a, 9b, 9c and 9d and is provided with a stripe shaped electrode 10 extending between sides 9c and 9d for grounding. Dielectric sheets 2 and 3 has exactly the same configuration. When they are laminated one over the other in a manner shown by chain lines in FIG. 2, electrodes 8 and 10 cross each other at a right angle. Accordingly, a part of electrode 8 confronts a part of electrode 10.
In the above described manner, a plurality of dielectric sheets 2 and 3 are laminated one over the other and, at the end, dielectric sheet 11, which has no electrode deposited thereon, is laminated, thereby defining a laminated block. It is to be noted that electrodes 8 on dielectric sheets 2 are all aligned in the first direction, and electrodes 10 on dielectric sheets 3 are all aligned in the second direction, which is at a right angle to the first direction. Then, external electrodes 4 and 5 are provided at opposite ends of laminated block so that external electrodes 4 and 5 are connected to electrode 8. Furthermore, external electrode 6 is provided intermediately between external electrodes 4 and 5 so that external electrode 6 is connected to electrode 10. Electrodes 4, 5 and 6 must be so extended to a surface of the laminated block, on which the circuit board confronts.
According to the prior art laminated capacitor of a feed-through type, the ends of electrodes 8 appear on opposite faces containing sides 7a, 9a and sides 7b and 9b, respectively. Furthermore, the ends of electrodes 10 appear on different opposite faces containing sides 7c, 9c and sides 7d and 9d, respectively. Accordingly, the face for providing external electrode 4 or 5 for the connection with electrode 8 is not flush with the face for providing external electrode 6 for the connection with electrode 10. Thus, in order to enable the electric connection of external electrodes 4, 5 and 6 to the electrode arrangement on a circuit board, it is necessary to extend the external electrodes 4, 5 and 6 around the edges so that they are contained in the same plane surface. To this end, according to the prior art laminated capacitor of FIG. 1, external electrodes 4 and 5 are prepared in a shape of a cap, and external electrode 6 is prepared in a belt that extends around the laminated block.
The prior art laminated capacitor has such disadvantages that it requires difficult steps before the external electrodes 4, 5 and 6 are completed, resulting in a high manufacturing cost. Furthermore, since external electrodes 4, 5 and 6 extend around an edge, e.g, 14, external electrodes 4, 5 and 6 might be undesirably cut at such an edge 14. Moreover, since the distance of the electrode between, e.g., electrode 10 and the electrode on the circuit board becomes relatively long, the residual inductance also becomes large, resulting in the deterioration of the capacitor characteristics.